Project Summary/Abstract: The twenty-first century has seen a global rise in human health problems caused by air pollution, and urban exposure to aerosolized particulate matter (PM) has been strongly linked to respiratory disease. Significant pulmonary health risks are associated with ultrafine PM (PM<2.5 m or PM2.5), whose levels exceed global urban air-quality standards for the majority of the world?s population and can lead to premature mortality. With the rapid growth of the nanotechnology sector, the release of engineered nanomaterials (ENMs; 1-100 nm) into the environment, deposition in the respiratory tract and the potential for toxicity are matters of growing concern. The nasal cavity serves as one of the first physical barriers to inhaled ENMs, where aerosolized nanoparticles can lodge in the nasal epithelial layer and induce toxicity responses. Although in vivo models have provided valuable toxicological data using defined mixtures of nanoparticles, responses in animal models do not always correlate to human toxicity responses. Hence, there is a growing need to develop, validate, and utilize new in vitro alternatives that physiologically reproduce the nasal microenvironment and provide more economical, ethical, and effective nanotoxicology platforms. We propose to develop an in vitro assay for toxicological analysis of nasal epithelia after aerosolized ENM exposure. During Phase I, we will demonstrate and test a vascularized airway microfluidic platform that incorporates primary, differentiated, nasal epithelial cells grown in an air-liquid interface (ALI). Following multiscale computational modeling of nanoparticle distribution dynamics in the human nasal cavity, we will evaluate the distribution and toxicity of selected aerosolized ENMs using the nasal ALI microfluidic model. Differential gene expression analysis of specific toxicology pathways will be performed, and the in vitro analysis will be validated against available in vivo data. Gene expression data will be integrated into our high-fidelity computational platform to demonstrate a systems-based analysis of ENM inhalation, distribution and toxicology. In Phase II, we will expand the platform through device multiplexing and linking the nasal and previously- developed lung ALI models together to form a combined respiratory inhalation model for nanotoxicology screening. The developed in vitro microphysiological platform with multiple endpoint analysis will provide a robust and cost-saving model for evaluating nanoparticle distribution, aggregation and respiratory toxicity responses in humans.